Colonoscopy is an outpatient procedure in which the rectum and the inside of the lower large intestine (colon) are examined. Colonoscopies are commonly used to evaluate bowel disorders, rectal bleeding or polyps (usually benign growths) found on contrast x-rays. Colonoscopies are also performed to screen people over age 50 for colon and rectal cancer. During a colonoscopy, a physician uses a colonoscope (a long, flexible instrument about ½ inch in diameter) to view the lining of the colon. The colonoscope is inserted through the rectum and advanced to the large intestine.
If necessary during a colonoscopy, small amounts of tissue can be removed for analysis (called a biopsy) and polyps can be identified and removed. In many cases, colonoscopy allows accurate diagnosis and treatment without the need for a major operation. However, in some cases the tissue cannot be removed during the colonoscopy and thus must be removed in a subsequent surgical procedure. In these situations, india ink or blue dye is topically injected during the preoperative colonoscopy to mark the tumor site. However, such a procedure includes the intrinsic danger of possibly injecting dye into the peritoneal cavity. In addition, the injected marker may also spread so widely that the intended site may become obscured.
Accordingly, there remains a need for improved methods and devices for marking tissue, such as the bowel wall.